Customers entering a participating Starbucks will find their device automatically recognising and connecting to the iTunes Wi-Fi Music Store without the need for a connection fee or hotspot log-in.
Users can then browse, preview and purchase tracks and albums from the iTunes store.
To celebrate the launch, staff at participating Starbucks stores will hand out 1.5 million 'Song of the day' cards each day between 2 October and 7 November, which can then be redeemed at the iTunes store.
The service will also include a 'Now Playing' feature which displays the name of the song playing in the Starbucks store at that moment.
Pricing and selection on the iTunes Wi-Fi Music Store are the same as at the regular iTunes Store.
Steve Jobs, chief executive at Apple, described the new service as "very cool ".
"Getting free access to the iTunes Wi-Fi Music Store and the Now Playing service at Starbucks is a great way for customers to discover new music," he said.
Howard Schultz, chairman of Starbucks, added that the new partnership combined Apple's "leadership in digital music" with the coffee chain's huge retail footprint to help customers "discover and acquire new music instantly".
The new service will debut in New York and Seattle on 2 October, and continue with a national rollout to 350 Starbucks stores in the San Francisco Bay area from 7 November.
This will be followed by 500 stores in Los Angeles in early February 2008, 300 stores in Chicago in March 2008 and additional markets throughout the US later in 2008.
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